One of the few suitors for Greece's biggest real estate project at the former international airport of Hellenikon threatened on Wednesday to pull out of the race, leaving only two contenders in the sale that has dragged on for about three years.

Just a day before a deadline for binding bids, Elbit Cochin Island, a unit of Israeli holding company Elbit Imaging, said it would not bid for the project unless Athens improved the terms of the deal.

"Regrettably, we cannot submit an offer unless certain essential clarifications are given and improvements made to the share purchase agreement,» an Elbit Cochin Island spokesman told Reuters.

Ownership rights and property taxation were also among the regulatory issues that Elbit Cochin wanted more clarity on, the spokesman said, adding the investor was still interested in the project.

Greece's privatisation agency HRADF, which is managing the sale, declined to comment.

Along with Elbit Cochin, Greek Lamda Development, UK-based London and Regional Properties and Qatari Diar, submitted last year non-binding bids for the 99-year lease and development of the 620-hectare site near central Athens.

But Qatari Diar, the property arm of Qatar's sovereign wealth fund, has already dropped out of the race.

Athens has not disclosed what revenues it expects to raise from Hellenikon, located at Athens' southern coast but it is seen as a key deal to help the country meet a 3.6 billion euro ($4.9 billion) privatisation target this year, under the terms of its international bailout.

Government officials have said it could attract more than 5 billion euros in investments and create thousands of jobs in the country, where unemployment has hit a record of 28 percent.

Greece has repeatedly missed privatisation targets. It has raised a total of 2.6 billion euros, far below the 22 billion targeted in its first EU/IMF bailout in 2010.

Hellenikon includes several abandoned Olympic venues built for the 2004 Games and a marina. Investors were first invited to express interest in 2011 but it took more than two years to settle zone planning issues and remove legal hurdles raised by opponents and local communities.

"The development of Hellenikon is a big opportunity for our country. An unexploited site, full of derelicts, will be turned into a new city,» Deputy Development Minister Notis Mitarachi told reporters this week.